Multinuclear NMR Spectroscopy Research Articles

Steric Influence on the Constitution of Beryllium Phosphine Complexes

AbstractThe phosphine complexes of beryllium chloride, bromide and iodide, [(PMe2Ph)2BeX2], [(PMePh2)2BeX2] and [(PPh3)BeX2]2 (X=Cl, Br, I) were prepared and characterised with multinuclear NMR spectroscopy. Additionally the molecular structure of dinuclear [(PPh3)BeCl2]2 was determined with single crystal X‐ray diffraction techniques. The threshold cone angle of the phosphines, below which two ligands can coordinate to the beryllium dihalide fragments, is between 136° and 145°. Halide‐chloride exchange in dichloromethane is observed for [(PPh3)BeBr2]2 and [(PPh3)BeI2]2, which leads to the formation of [(PPh3)BeCl2]2. Due to the relatively low Lewis basicity of PPh3, it almost exclusively acts as a spectator ligand with only little formation of phosphonium cations.

Structural and Magnetization Dynamics of Borohydride-Bridged Rare-Earth Metallocenium Cations.

The structure and magnetic properties of the bimetallic borohydride-bridged dysprosocenium compound [{(η5-Cpttt)(η5-CpMe4t)Dy}2(μ:κ2:κ2-BH4)]+[B(C6F5)4]- ([3Dy][B(C6F5)4]) are reported along with the solution-phase dynamics of the isostructural yttrium and lutetium analogues (Cpttt is 1,2,4-tri(tert-butyl)cyclopentadienyl, CpMe4t is tetramethyl(tert-butyl)cyclopentadienyl). The synthesis of [3M][B(C6F5)4] was accomplished in the 2:1 stoichiometric reactions of [(η5-Cpttt)(η5-CpMe4t)Dy(BH4)] (2M) with [CPh3][B(C6F5)4], with the metallocenes 2M obtained from reactions of the half-sandwich complexes [(η5-Cpttt)M(BH4)2(THF)] (1M) (M = Y, Dy, Lu) with NaCpMe4t. Crystallographic studies show significant lengthening of the M···B distance on moving through the series 1M, 2M, and 3M, with essentially linear {M···B···M} bridges in 3M. Multinuclear NMR spectroscopy indicates restricted rotation of the Cpttt ligands in 3Y and 3Lu in solution. The single-molecule magnet (SMM) properties of [3M][B(C6F5)4] are characterized by Raman and Orbach processes, with an effective barrier of 533(18) cm-1 and relaxation via the second-excited Kramers doublet. Although quantum tunneling of the magnetization (QTM) was not observed for [3M][B(C6F5)4], it was, surprisingly, found in its magnetically dilute version, which has a very similar barrier of Ueff = 499(21) cm-1. Consistent with this observation, slightly wider openings of the magnetic hysteresis loop at 2 K are found for [3M][B(C6F5)4] but not for the diluted analogue. The dynamic magnetic properties of the dysprosium SMMs and the role of exchange interactions in 3Dy are interpreted with the aid of multireference ab initio calculations.

Cu(I) and Ag(I) complexes of two sterically demanding Xylyl-Substituted phosphine Ligands: Synthesis, Characterization, and structural examination

Two sterically demanding tertiary phosphines, PiPr2Xyl and PtBu2Xyl, (Xyl = 2,6-dimethylphenyl), the latter reported here for the first time, have been used to synthesize a series of dinuclear complexes of the general formula [M(μ-X)PR2Xyl]2, (R = iPr, tBu; M = Cu: X = Cl, Br, I, OTf; M = Ag: X = OTf, NTf2). All compounds have been characterized by multinuclear NMR spectroscopy in solution and, with the exception of AgNTf2(PtBu2Xyl), by X-ray diffraction analyses. The doubly halido-bridged compounds [Cu(μ-X)PR2Xyl]2 (R = iPr, tBu; X = Cl, Br, I) display Ci, C2-like, or C1 molecular symmetry, depending on the anion and the R group, and enclose planar or disphenoidal [CuX]2 cores with short, bonding Cu—Cu distances in case of X = I. On the other hand, centrosymmetric 8-membered rings with twist-chair conformations are found in the solid state structures of [M(μ-OTf)PR2Xyl]2 (R = iPr, tBu; M = Cu, Ag) and [Ag(μ-NTf2)PiPr2Xyl]2, with the anions in a κ2-μ2 coordination mode. Additionally, the cationic complex [Cu(PR2Xyl)2]+ has been obtained as a triflate or BArF salt (BArF- = B{3,5-(CF3)2C6H3}4-), and shows C2-like symmetry in the solid state, with PCuP angles of ca. 168-169° and synclinal dispositions of the Xyl groups with respect to the P∙∙∙P axis. Comparative discussion of relevant NMR data of Cu(I), Ag(I), and Au(I) adducts of the title phosphines is also provided.

Divalent ansa-Octaphenyllanthanocenes: Synthesis, Structures, and EuII Luminescence.

Reductive dimerization of fulvenes using low-valent metal precursors is a straightforward one-step approach to access ethylene-bridged metallocenes. This process has so far mainly been employed with fulvenes carrying one or two substituents in the exocyclic position. In this work, a new synthesis of the unsubstituted exocyclic 1,2,3,4-tetraphenylfulvene (1), its full structural characterization by NMR spectroscopy and single-crystal X-ray diffraction, as well as some photophysical properties and its first use in reductive dimerization are described. This fulvene reacted with different lanthanoid metals in thf to provide the divalent ansa-octaphenylmetallocenes [Ln(C5Ph4CH2)2(thf)n] (Ln = Sm, n = 2 (2); Ln = Eu, n = 2 (3); and Ln = Yb, n = 1 (4)). These complexes were characterized by X-ray diffraction, laser desorption/ionization time of flight mass spectrometry, and, in the case of Sm and Yb, multinuclear NMR spectroscopy, showing the influence of the ansa-bridge on solution and solid-state structures compared to previously reported unbridged metallocenes. Furthermore, the luminescence properties of the Eu ansa complex 3 were studied in solution and the solid state, revealing significant differences with the known octa- and deca-phenyleuropocenes, [Eu(C5Ph4H)2(dme)] and [Eu(C5Ph5)2].

Lithium fluoroarylsilylamides and their structural features

Abstract In order to probe the role of Li⋯F interactions toward the stabilisation of low-coordinate lithium complexes, the four fluoroarylsilylamides [LiN(SiMe3)(2-C6H4F)] (1-Li), [LiN(SiMe3)(2,6-C6H3F2)] (2-Li), [LiN(SiMe3)(C6F5)] (3-Li), and [LiN(SiMe2H)(2-C6H4F)] (4-Li) have been synthesised in high yields by deprotonation of the parent amines with nBuLi. They have been comprehensively characterised by multinuclear NMR spectroscopy, and complete assignments were achieved with the help of 2D NMR data. The molecular solid-state structures of [(2-Li)2]∞, [3-Li·Et 2 O]2, and [4-Li]8 were determined by single-crystal X-ray diffraction. They feature unusual coordination patterns, notably for the formation of the polymeric [(2-Li)2]∞ and a unique octagonal, crown-like [4-Li]8. In both structures, the role of Li⋯F non-covalent interactions was the key toward the building of the final architecture. It is shown that Li–F and C–F interatomic distances, along with |1 J C,F| coupling constants, can be used as qualitative tools for the evaluation of the presence and relative strength of Li⋯F contacts.

4,5-Di-tert-butyl-1,3,6,8-tetraphenyl-4,5,8a,8b-tetrahydro-as-indacene

Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5H2)2]K2(THF)3 1, in dry MeCN facilitated an intramolecular cyclopentadienyl ring-C to ring-C bond formation and the precipitation of the crude product 4,5-di-tert-butyl-1,3,6,8-tetraphenyl-4,5,8a,8b-tetrahydro-as-indacene 2 as an off-white solid in a 73% yield (>95% pure, 1H NMR). Characterization of 2 was carried out using multinuclear NMR spectroscopy (1H and 13C), single-crystal X-ray crystallography, FTIR spectroscopy, and thermal analytical techniques (SDT, DSC). The molecular structure consisted of a rigid, C2-symmetric six-membered ring in a chair conformation with four of the ring-C atoms fused to 1,3-diphenylcyclopentadiene rings and the other two ring-C atoms substituted with trans di-axial But groups.

C- and N-Phosphorylated Enamines-An Avenue to Heterocycles: NMR Spectroscopy.

The review presents extensive data (from the works of the author and literature) on the structure of C- and N-chlorophosphorylated enamines and the related heterocycles obtained by multipulse multinuclear 1H, 13C, and 31P NMR spectroscopy. The use of phosphorus pentachloride as a phosphorylating agent for functional enamines enables the synthesis of various C- and N-phosphorylated products that are heterocyclized to form various promising nitrogen- and phosphorus-containing heterocyclic systems. 31P NMR spectroscopy is the most convenient, reliable and unambiguous method for the study and identification of organophosphorus compounds with different coordination numbers of the phosphorus atom, as well as for the determination of their Z- and E-isomeric forms. An alteration of the coordination number of the phosphorus atom in the phosphorylated compounds from 3 to 6 leads to a drastic screening of the 31P nucleus from about +200 to -300 ppm. The unique structural features of nitrogen-phosphorus-containing heterocyclic compounds are discussed.

Phosphine–Stibine and Phosphine–Stiborane peri-Substituted Donor–Acceptor Complexes

Two novel Sb(III) and Sb(V) peri-substituted acenaphthene phosphorus−antimony compounds were prepared. The Sb(III) compound, 1, was prepared via reacting the organolithium precursor with dichloro(p-tolyl)Stibine, and 2 was prepared by the chlorination of 1. Both 1 and 2 were characterized by multinuclear (1H, 13C and 31P) NMR spectroscopy, and their molecular structures resolved by single-crystal X-ray diffraction. Both compounds show a dative P−Sb interaction with the antimony being the acceptor group in both cases owing to its Lewis acidity.

Alkyl‐Bridged Nitropyrazoles – Adjustment of Performance and Sensitivity Parameters

AbstractStarting from 3,5‐dinitro‐4‐methylaminopyrazole (2), six different energetic salts and three new derivatives of methylene bridged nitropyrazoles were synthesized. The derivatives bear a methylamino (4), methylnitramino (5), and azido group (7). All compounds were intensively characterized using single crystal X‐ray diffraction, multinuclear NMR spectroscopy, IR spectroscopy, mass spectrometry, elemental analysis and DTA/TGA measurements. The sensitivities were determined according to BAM standard methods and the energetic properties calculated using the EXPLO5 code. The energetic salts were compared with each other and with ANTA in terms of their energetic properties. On the basis of the methyl‐ and ethyl bridged derivatives, it was shown how the introduction of methylamino (4) and methylnitramino (5) groups in an alkyl‐bridged nitropyrazole system modify its properties (performance & sensitivities). In addition, azido compound 7 was contrasted with its literature‐known constitutional isomer and investigated for its suitability as a potential metal‐free primary explosive.

New organobismuth(III) compounds based on a tetrahydro-dibenzo[c,f][1,5] azabismocine heterocyclic framework

Organobismuth chalcogenides of type [CH3OCH2CH2N(CH2C6H4)2Bi]2E [E = S (1), Se (2)], containing two butterfly-like tetrahydro-dibenzo[c,f][1,5]azabismocine heterocyclic frameworks, were prepared and their solution behavior was investigated by multinuclear NMR spectroscopy (1H, 13C and 77Se, as appropriate) and mass spectrometry. Crystals of [CH3OCH2CH2N(CH2C6H4)2BiO]2SeO (3) were serendipitously formed during the synthesis of compound 2. The molecular structure of 3 was determined by single-crystal X-ray diffraction and revealed, besides a strong transannular N→Bi interaction, an additional O‧‧‧Bi interaction involving the oxygen of the NCH2CH2OCH3 pendant arm from the organic fragment attached to the metal atom, thus resulting in a 12Bi5 hypercoordinate species.

Ruthenium(II) Tris‐Pyrazolylmethane Complexes in Transfer Hydrogenation Reactions

AbstractWhile ruthenium(II) arene complexes have been widely investigated for their potential in catalytic transfer hydrogenation, studies on homologous compounds replacing the arene ligand with the six‐electron donor tris(1‐pyrazolyl)methane (tpm) are almost absent in the literature. The reactions of [RuCl(κ3‐tpm)(PPh3)2]Cl, 1, with a series of nitrogen ligands (L) proceeded with selective PPh3 mono‐substitution, affording the novel complexes [RuCl(κ3‐tpm)(PPh3)(L)]Cl (L=NCMe, 2; NCPh, 3; imidazole, 4) in almost quantitative yields. Products 2–4 were fully characterized by IR and multinuclear NMR spectroscopy, moreover the molecular structure of 4 was ascertained by single crystal X‐ray diffraction. Compounds 2–4 were evaluated as catalytic precursors in the transfer hydrogenation of a series of ketones with isopropanol as the hydrogen source, and 2 exhibited the highest activity. Extensive NMR experiments and DFT calculations allowed to elucidate the mechanism of the transfer hydrogenation process, suggesting the crucial role played by the tpm ligand, reversibly switching from tri‐ to bidentate coordination during the catalytic cycle.

Access to Bis(σ‐B−H) Complexes of Ruthenium Bearing Monoaryl Borate and Borane Ligands

AbstractA series of ruthenium bis(σ‐B−H) borate complexes 1–4 have been prepared by a salt‐elimination protocol using lithium monoaryl trihydroborates Li[ArBH3] (R=Ph, 3,5‐(CF3)2C6H3, o‐tol or Mes) and the corresponding metal halide Cp*Ru(PCy3)Cl. All of these bis(σ‐B−H) borate complexes are stable at room temperature and isolated in good yields (70–92 %). Additionally, treatment of 4 with the hydride abstracting agent B(C6F5)3 generated rare cationic bis(σ‐B−H) borane complex 5. Crystallographic characterization data are provided for 3 and 5. All these new complexes were fully characterized by multinuclear NMR spectroscopy and elemental analysis.

Influence of the Steric/Electronic Properties of N-Aryl Substituents in Cycloplatinated Guanidinate(1−) Complexes on the Formation of Discrete Pt → Ag Complexes and One-Dimensional Coordination Polymer

The reactions of cycloplatinated guanidinate(1-) complexes 1-6 with AgTFA (TFA = OC(O)CF3) in 1:1 and 1:2 PtII/AgI molar ratios afforded complexes containing three types of Pt2Ag2 skeletons (7-10, 11, and 13), one 1D CP containing Pt2Ag3 skeleton (16), and a Pt2Ag4 complex (17) in 91-95% (method 1), 73-82% (method 2) (7-10), and 54-79% (11, 13, 16, and 17) yields. The reactions of 11 with 2,6-XylNC (2,6-Xyl = 2,6-Me2C6H3) and 4-DMAP (4-dimethylaminopyridine) gave a neutral complex 18 and an ionic complex 19, respectively. Molecular structures of 12 complexes were unambiguously determined by single-crystal X-ray diffraction. Ten complexes contain unprecedented PtAg skeletons and are shown to contain multiple number of dative Pt → Ag bonds supported by the TFA ligand, platinated carbon of the TAG ligand, or both these ligands in conjunction with the Ag-Ag contacts stabilized by argentophilic interaction. Further, the new complexes were characterized by analytical, IR, and multinuclear NMR (19F, 1H, 13C{1H}, and 195Pt) spectroscopies, powder X-ray diffraction, and TGA/DTA. In solution, 9 and 19 exist in more than one form as identified by multinuclear NMR, and this behavior is ascribed to the restricted (N2)C-N(H)Ar single-bond rotation of the TAG ligand. The photophysical properties of 9 and 11 are reported.

C, N-chelated antimony and bismuth complexes; oxidation and fluorination

A set of organoantimony(III/V) and organobismuth(V) fluorides (i.e. LSbF2, LSbClF, LPh2SbF2, LSbF4 and LPh2BiF2) bearing the 2-{[(2,6-diisopropylphenyl)imino]methyl}phenyl- as a C,N-chelating ligand (L) has been prepared using LCNR2SnF (where LCN = 2-(N,N-dimethylaminomethyl)phenyl); R = n-Bu or Ph) and/or XeF2 as fluorinating agents. All species were characterised by the combination of elemental analysis and multinuclear solution NMR spectroscopy. Solid-state structures of all complexes were established by the sc-XRD analysis. In addition, theoretical calculations were carried out to corroborate the experimental results. Preparation and structural characterisation of LSbI2 is also reported.

Studies Relevant to the Functional Model of Mo-Cu CODH: In Situ Reactions of Cu(I)-L Complexes with Mo(VI) and Synthesis of Stable Structurally Characterized Heterotetranuclear MoVI2CuI2 Complex.

In this study, we report the synthesis, characterization, and reactions of Cu(I) complexes of the general form Cu(L)(LigH2) (LigH2 = xanthene-based heterodinucleating ligand (E)-3-(((5-(bis(pyridin-2-ylmethyl)amino)-2,7-di-tert-butyl-9,9-dimethyl-9H-xanthen-4-yl)imino)methyl)benzene-1,2-diol); L = PMe3, PPh3, CN(2,6-Me2C6H3)). New complexes [Cu(PMe3)(LigH2)] and [CuCN(2,6-Me2C6H3)(LigH2)] were synthesized by treating [Cu(LigH2)](PF6) with trimethylphosphine and 2,6-dimethylphenyl isocyanide, respectively. These complexes were characterized by multinuclear NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry (HRMS), and X-ray crystallography. In contrast, attempted reactions of [Cu(LigH2)](PF6) with cyanide or styrene failed to produce isolable crystalline products. Next, the reactivity of these and previously synthesized Cu(I) phosphine and isocyanide complexes with molybdate was interrogated. IR (for isocyanide) and 31P NMR (for PPh3/PMe3) spectroscopy demonstrates the lack of oxidation reactivity. We also describe herein the first example of a structurally characterized multinuclear complex combining both Mo(VI) and Cu(I) metal ions within the same system. The heterobimetallic tetranuclear complex [Cu2Mo2O4(μ2-O)(Lig)2]·HOSiPh3 was obtained by the reaction of the silylated Mo(VI) precursor (Et4N)(MoO3(OSiPh3)) with LigH2, followed by the addition of [Cu(NCMe)4](PF6). This complex was characterized by NMR spectroscopy, high-resolution mass spectrometry, and X-ray crystallography.

Synthesis and Characterization of Xylazine Hydrochloride Polymorphs, Hydrates, and Cocrystals: A 35Cl Solid-State NMR and DFT Study

Xylazine HCl (X) is a veterinary analgesic with many known solid forms, making it an ideal system for studying the noncovalent interactions, such as hydrogen bonding, that provide stability to polymorphs, solvates/hydrates, and cocrystal of pharmaceuticals. Herein, we report methods for the reliable preparation and interconversion of polymorphs of X (including mechanochemical pathways), the discovery of a novel polymorph, and the synthesis of three cocrystals with coformers containing amide and carboxylic acid moieties. An understanding of ball milling protocols is essential for optimizing these reactions and ensuring clean and reproducible syntheses of the products in high yields. All materials were characterized using thermal analysis, powder and single-crystal X-ray diffraction (PXRD and SCXRD), and multinuclear solid-state NMR (SSNMR) spectroscopy. 35Cl SSNMR is highlighted for its versatility for fingerprinting polymorphs, hydrates, and cocrystals (including the detection of impurity phases that are not always evident from PXRD and offering an avenue for optimizing synthetic protocols) and providing molecular-level structural information. The 35Cl electric field gradient (EFG) tensor is extremely sensitive to the unique hydrogen-bonding network in each solid form of X, resulting in distinct powder patterns. Dispersion-corrected plane-wave density functional theory (DFT) structural refinements yield better models of the hydrogen-bonding environments of the chloride ions than is possible through XRD methods alone. Calculations employing the refined structures yield 35Cl EFG tensors that agree well with experiment. PXRD and 35Cl SSNMR, in tandem with reliable calculations of EFG tensors, are essential for the development of NMR crystallographic and crystal structure prediction protocols and crucial for future studies involving HCl salts and their concomitant solid forms.

Synthesis of novel 2- and 8-substituted 4-amino-7-chloroquinolines and their N-alkylated coupling products

The synthesis of a series of 2- and 8-substituted 4-amino-7-chloroquinolines is presented. Starting from 4,7-dichloroquinolines, the chloro in the 4-position can be effectively substituted using amino alcohols to yield novel analogues of the antimalarial (hydroxy)chloroquine. Both short-chain (2-aminoethanol) and long-chain (5-[ N-ethyl- N-(2-hydroxyethyl)amino]-2-aminopentane) coupling partners can be used. While ketone and nitro functionalities were found to be incompatible with the coupling conditions, electron-donating amino and dimethylamino substituents were tolerated. In addition to characterization in solution using multinuclear NMR spectroscopy and high-resolution mass spectrometry, single-crystal X-ray structures are presented of two 4,7-dichloroquinolines as well as three of the N-alkylated products including a unique species in which a pyrrole heterocycle formed at the 2-position of the quinoline subunit and a rare example of a 4-aza-1,10-phenanthroline.

Controlled Shell and Kernel Modifications of Atomically Precise Pd/Ag Superatomic Nanoclusters.

The first 8-electron Pd/Ag superatomic alloys with an interstitial hydride [PdHAg19(dtp)12] (dtp = S2P(O i Pr)2-) 1 and [PdHAg20(dtp)12]+2 are reported. The targeted addition of a single Ag atom to 1 is achieved by the reaction of one equivalent of trifluoroacetic acid, resulting in the formation of 2 in 55% yield. Further modification of the shell results in the formation of [PdAg21(dtp)12]+3 via an internal redox reaction, with the system retaining an 8-electron superatomic configuration. The interstitial hydride in 1 and 2, contributes its 1s1 electron to the superatomic electron count, and occupies a PdAg3 tetrahedron. The distributions of isomers corresponding to different dispositions of the outer capping Ag atoms are investigated by multinuclear VT-NMR spectroscopy. The emissive state of 3 has a lifetime of 200 μs (λex =448; λem =842), while 1 and 2 are non-emissive. The catalytic reduction of 4-nitrophenol is demonstrated with 1-3 at room temperature.

Cyclic and Macrocyclic Molecules Containing Silicon or Tin – Synthesis of Highly Rigid, Potentially Lewis‐Acidic Cryptands

AbstractHerein we report the syntheses of highly rigid silicon‐ and tin‐containing cyclic and bicyclic compounds with unsaturated organic backbones. The syntheses proceed via di‐lithiated diethynylbenzene derivatives. The protocols for the known precursor compounds were significantly improved in a two‐step one‐pot reaction with yields up to 45 % by alternating addition of the lithiation reagent and starting material. A total of ten compounds were synthesized and the molecular structure in the solid state was elucidated for six novel compounds. Host‐guest‐experiments with selected molecules were conducted to investigate on the potential of the complexation of small anions. All compounds were characterized by multinuclear NMR spectroscopy and elemental analyses or mass spectrometry and in most parts by SC‐XRD analyses.

Diiron Aminocarbyne Complexes with NCE- Ligands (E = O, S, Se).

Diiron μ-aminocarbyne complexes [Fe2Cp2(NCMe)(CO)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Xyl, [1aNCMe]CF3SO3; R = Me, [1bNCMe]CF3SO3; R = Cy, [1cNCMe]CF3SO3; R = CH2Ph, [1dNCMe]CF3SO3), freshly prepared from tricarbonyl precursors [1a-d]CF3SO3, reacted with NaOCN (in acetone) and NBu4SCN (in dichloromethane) to give [Fe2Cp2(kN-NCO)(CO)(μ-CO){μ-CN(Me)(R)}] (R = Xyl, 2a; Me, 2b; Cy, 2c) and [Fe2Cp2(kN-NCS)(CO)(μ-CO){μ-CN(Me)(CH2Ph)}], 3 in 67-81% yields via substitution of the acetonitrile ligand. The reaction of [1aNCMe-1cNCMe]CF3SO3 with KSeCN in THF at reflux temperature led to the cyanide complexes [Fe2Cp2(CN)(CO)(μ-CO){μ-CNMe(R)}], 6a-c (45-67%). When the reaction of [1aNCMe]CF3SO3 with KSeCN was performed in acetone at room temperature, subsequent careful chromatography allowed the separation of moderate amounts of [Fe2Cp2(kSe-SeCN)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 4a, and [Fe2Cp2(kN-NCSe)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 5a. All products were fully characterized by elemental analysis, IR, and multinuclear NMR spectroscopy; moreover, the molecular structure of trans-6b was ascertained by single crystal X-ray diffraction. DFT calculations were carried out to shed light on the coordination mode and stability of the {NCSe-} fragment.